Shielded electrical connector systems are used in many applications, including telecommunications equipment, computers, other digital information systems, and the like. The electrical circuitry in such applications include electrical cables having a plurality of electrically conductive leads surrounded and protected by an electrically conductive shield, such as a braid, foil or the like. In most such applications, it is necessary to shield the signal-carrying circuits to avoid electromagnetic interference caused by energy generated outside of as well as inside the system, thus "hardening" the system to the ingress and egress of radiated emissions.
Many such electrical connectors are used in conjunction with systems which incorporate printed circuit boards to which the connectors are surface-mounted. The board is provided with ground planes or ground circuits to which the connectors are conductively coupled. The coupling usually is through the shields of the connectors.
One type of miniature electrical connector of the character described is commonly called a circular DIN connector (or a "mini-DIN" connector) and is known to include a dielectric housing in which electrical terminals are mounted. The mini-DIN connector usually is rectangularly shaped in cross-section and a rectangular body or housing has a top, bottom, front, rear and opposite sides. The front of the housing defines a mating end for receiving a projecting portion of a mating connector or cable plug. This mating end includes a circular recess within which a circular cross-sectional plug portion projects forwardly for receiving a circular cross-sectional, externally shielded electrical socket of the mating connector. A rectangularly configured shield is disposed about portions of the housing and has means for making electrical contact with the shield of the mating connector. The shield usually is fabricated from stamped and formed sheet metal material. The metal shield may include a front wall over the front of the housing, the front wall including a series of spring fingers for making electrical contact with the shielding of the mating connector. In addition to the front wall, the shield may include one or more of a top wall over the top of the housing; a rear wall over the rear of the housing and opposite side walls over the opposite sides of the housing.
Another type of rectangular shielded electrical connector assembly of the character described is a telecommunications connector or jack which also is rectangular of "box"-shaped and includes a rectangularly-shaped dielectric housing having portions of the outside thereof covered by a stamped and formed metal shield having planar walls covering some of the outside walls of the housing, similar to the circular mini-DIN connector. An example of a shield for such a telecommunications connector is shown in U.S. Pat. No. 5,083,945, dated Jan. 28, 1992, and which is assigned to the assignee of the present invention.
One of the problems with shielded electrical connector assemblies as described above involves mounting the connector including the shield to the printed circuit board. The most common mounting system includes a plurality of mounting members such as tabs or tails formed integrally with the shield, usually the side walls of the shield, and projecting through and soldered within holes in the printed circuit board. This configuration provides strain relief for the fragile terminals particularly when they are surface mounted to contact pads of the circuitry on the printed circuit board. It may further provide an electrical connection such as a ground connection to the circuitry. However, with the increasing miniaturization and complexity of circuit design, such hole-mounted tails often cannot be used, particularly where circuit components are mounted on both sides of a printed circuit board. In such applications, mounting members cannot project through the board where they might interfere with circuit components on the opposite side of the board. Therefore, separate metal retaining plates have been proposed to secure a surface mounted connector to a contact pad of a printed circuit board, as shown in U.S. Pat. No. 5,096,440, dated May 17, 1992. Such separate metal retaining plates have first portions anchored to the connector housing and second portions reflow soldered to the pads on the printed circuit board. Unfortunately however, the use of such separate retaining plates may add considerably to the overall cost of manufacturing the connectors and assembling the connectors to the printed circuit board. Furthermore, the plates may use up valuable printed circuit board "real estate" when the plate is not located substantially with the peripheral envelope of the connector assembly.
Another continuing problem with shielded electrical connector assemblies of the character described above involves providing adequate grounding of the connector shield to the printed circuit board. As stated above, the shields are electrically coupled to shielded mating connectors and associated shielded cables, and the shields therefore must be connected to ground traces on the printed circuit board. This must be done in order to establish and maintain effective shielding of the attached shielded cables and their associated peripherals. This invention is directed to various schemes which improve the grounding network of such shielded connectors.
Still further, some shields are fabricated of a plurality of parts, such as a two-piece shield, for various reasons, including cost effectiveness. Unfortunately, it has been difficult to common the parts of the shield to provide adequate shielding and grounding throughout the entire connector assembly. This invention is directed to providing improvements in plural component shields to enhance the shielding and grounding characteristics thereof.